The company said there were about 48,800 patients on Tysabri at the
end of the quarter.

Biogen also took about $33 million in impairment charges in the
fourth quarter of 2008. Those charges were related to the declining
value of its marketable securities and strategic investments.

For the full year 2009, Biogen said its profit grew 24 percent to
$970.1 million, or $3.35 per share, from $783.2 million, or $2.65
per share, in 2008. Revenue grew 7 percent to $4.38 billion from
$4.1 billion.

The company forecast a profit of at least $3.71 per share in 2010,
or more than $4.55 per share excluding one-time costs. It said
revenue will grow in the mid-single digits.

Analysts are expecting a profit of $4.38 per share and $4.52
billion in revenue, which implies sales growth of about 3
percent.